This invention is directed to methods and products employing thiazolides to treat and prevent influenza infection.
Influenza, a highly contagious acute respiratory illness affecting all age groups, causes about 36,000 deaths and over 226,000 hospitalizations per year in the United States alone. Classified (as types A, B, and C), according to antigenic differences in their nucleoprotein and matrix protein, the influenza viruses are enveloped, negative-stranded RNA viruses; the A type is the most important clinically. The many subtypes of influenza A virus differ in their two surface glycoproteins, hemagglutinin (“HA”) and neuraminidase (“NA”), which are the main targets of the protective immune response, and are labeled according to the type of hemagglutinin (denoted with an H number) and neuraminidase (denoted with an N number). HA and NA vary continuously as a result of antigenic drift and antigenic shift. Sixteen H subtypes (or “serotypes”) and nine N subtypes are known.
The emergence of highly pathogenic influenza A virus strains, such as the new H1N1 swine influenza, represents a particularly serious threat to global human health. In addition to surveillance and early diagnosis, efforts to control emerging influenza strains have emphasized the development of both effective vaccines and novel antiviral drugs.
Influenza A virus hemagglutinin is a trimeric glycoprotein that contains 3-9 N-linked glycosylation sequons per subunit, depending on the strain. HA is initially synthesized and core-glycosylated in the endoplasmic reticulum as a 75-79 kDa precursor (HA0) which assembles into noncovalently linked homo-trimers. The trimers are rapidly transported to the Golgi complex and reach the plasma membrane, where HA insertion initiates the process of assembly and maturation of the newly formed viral particles. Just prior to or coincident with insertion into the plasma membrane, each trimer subunit is proteolytically cleaved into two glycoproteins, HA1 and HA2, which remain linked by a disulfide bond.